Support of flexible component and light-emitting device

ABSTRACT

To provide a support for supporting a flexible component and a light-emitting device. A first substrate, a second substrate, a rack, a pinion, and a hinge are provided. When the second substrate is moved, the rotational force of the pinion is transmitted to the rack of the first substrate and thus the first substrate is moved in the horizontal direction while being overlapped with one of hinge pieces of the hinge; accordingly, the flexible component can be bent while the flexible component is fixed to the first substrate and the second substrate and the allowable curvature radius is maintained in the vicinity of the hinge.

BACKGROUND OF THE INVENTION 1. Field of the Invention

One embodiment of the present invention relates to a support of aflexible component, and a light-emitting device.

Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of thepresent invention disclosed in this specification and the like relatesto an object, a method, or a manufacturing method. In addition, oneembodiment of the present invention relates to a process, a machine,manufacture, or a composition of matter. Specifically, examples of thetechnical field of one embodiment of the present invention disclosed inthis specification include a semiconductor device, a display device, aliquid crystal display device, a light-emitting device, a lightingdevice, a power storage device, a storage device, an imaging device, amethod for driving any of them, and a method for manufacturing any ofthem.

In this specification and the like, a semiconductor device generallymeans a device that can function by utilizing semiconductorcharacteristics. A transistor and a semiconductor circuit areembodiments of semiconductor devices. In some cases, a storage device, adisplay device, an imaging device, or an electronic device includes asemiconductor device.

2. Description of the Related Art

In recent years, research and development have been extensivelyconducted on light-emitting elements utilizing electroluminescence (EL).In a basic structure of such a light-emitting element, a layercontaining a light-emitting substance is interposed between a pair ofelectrodes. By applying voltage to the element, light emission from thelight-emitting substance can be obtained.

The above light-emitting element is a self-luminous element; thus, alight-emitting device including the light-emitting element hasadvantages such as high visibility, no necessity of a backlight, and lowpower consumption. In addition, the light-emitting device has advantagesin that it can be manufactured to be thin and lightweight and has fastresponse speed.

Since a light-emitting device including the above light-emitting elementcan have flexibility, use of the light-emitting device for a flexiblesubstrate has been proposed.

As a method for manufacturing a light-emitting device using a flexiblesubstrate, a technology in which a separation layer is formed over asubstrate, e.g., a glass substrate or a quartz substrate, asemiconductor element such as a thin film transistor is formed over theseparation layer, and then, the semiconductor element is transferred toanother substrate (e.g., a flexible substrate) has been developed (seePatent Document 1).

REFERENCE Patent Document [Patent Document 1] Japanese Published PatentApplication No. 2003-174153 SUMMARY OF THE INVENTION

Components such as a light-emitting device formed over a flexiblesubstrate can improve portability by being folded utilizing theirflexibility. On the other hand, sufficient mechanical strength cannot beobtained because of their small thicknesses. For these reasons, asupport having sufficient mechanical strength is preferably provided toprotect the flexible component from external damage or unexpected shockin carrying.

Although the flexible component can be bent to a certain degree, aninternal structure is physically broken when the flexible component isbent with an extremely small curvature radius. For that reason, evenwhen the support is used for protection, a bendable region of theflexible component has to maintain the allowable curvature radius.

For example, a foldable support includes two boards connected by ahinge, and one flexible component (e.g., a light-emitting device) isacross the two boards in a state where the support is opened. Here, tofold the support safely without breaking the flexible component, it isnecessary to maintain the allowable curvature radius of the flexiblecomponent in the vicinity of the hinge.

Maintaining the curvature radius can be easily achieved without devisingthe hinge in the following manner: the flexible component is fixed toone of the two boards connected by the hinge and fixed to the otherboard so as to be slid in the horizontal direction. However, the designis poor and the reliability is decreased.

Thus, an object of one embodiment of the present invention is to providea support for supporting a flexible component. Another object is toprovide a support for performing bending operation without decreasingthe reliability of a flexible component. Another object is to provide asupport for maintaining the allowable curvature radius of a flexiblecomponent. Another object is to provide a support for improving thereliability of a flexible component. Another object is to provide asupport for suppressing a decrease in electrical characteristics of aflexible component. Another object is to provide a novel support of aflexible component. Another object is to provide a novel light-emittingdevice.

Note that the description of these objects does not disturb theexistence of other objects. In one embodiment of the present invention,there is no need to achieve all the objects. Other objects will beapparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

The present invention relates to a support of a flexible component, asupport of a flexible component for performing bending operation stablywithout breaking the flexible component, and a light-emitting deviceincluding the flexible component. Note that the support of the flexiblecomponent serves as a protector of the flexible component in some casesdepending on the purpose or situations.

According to one embodiment of the present invention, a support of aflexible component includes a first substrate, a second substrate, arack, a pinion, and a hinge. The rack is fixed to a corner of the firstsubstrate. A center of the pinion is fixed to a shaft of the hinge. Aslide function is provided in one of hinge pieces of the hinge. Theshaft of the hinge is fixed to the other of the hinge pieces of thehinge. The hinge is provided over the first substrate and the secondsubstrate so that teeth of the rack and teeth of the pinion engage witheach other in a state where the second substrate is adjacent to the sideof the corner of the first substrate to which the rack is fixed. Thefirst substrate and the one of the hinge pieces of the hinge are fixedto each other in a state where the first substrate can be moved in ahorizontal direction with the slide function while being overlapped withthe one of the hinge pieces of the hinge. The second substrate and theother of the hinge pieces of the hinge are fixed to each other. When thesecond substrate is moved, a rotational force of the pinion istransmitted to the rack, and thus the first substrate is moved in thehorizontal direction while being overlapped with the one of the hingepieces of the hinge.

Note that in this specification and the like, ordinal numbers such as“first” and “second” are used in order to avoid confusion amongcomponents and do not limit the components numerically.

One flexible component can be fixed to the support of the flexiblecomponent across the first substrate and the second substrate, andbending operation can be performed without breaking the flexiblecomponent.

The first substrate and the second substrate can be connected to eachother with two sets of the hinge and peripheral components (a rack, apinion, and the like).

According to another embodiment of the present invention, a support of aflexible component includes a first substrate, a second substrate, athird substrate, a first rack, a second rack, a first pinion, a secondpinion, a third pinion, an intermediate gear, a first hinge, and asecond hinge. The first rack is fixed to a corner of the secondsubstrate. A center of the first pinion is fixed to a shaft of the firsthinge. A shaft of the first hinge is fixed to one of hinge pieces of thefirst hinge. A first slide function is provided in the other of thehinge pieces of the first hinge. The first hinge is provided over thefirst substrate and the second substrate so that teeth of the first rackand teeth of the second pinion engage with each other in a state wherethe first substrate is adjacent to the side of the corner of the secondsubstrate to which the first rack is fixed. The second substrate and theother of the hinge pieces of the first hinge are fixed to each other ina state where the second substrate can be moved in a horizontaldirection with the first slide function while being overlapped with theother of the hinge pieces of the first hinge. The first substrate andthe one of the hinge pieces of the first hinge are fixed to each other.The second rack is fixed to a corner of the third substrate. A center ofthe second pinion is fixed to a shaft which is fixed to one of hingepieces of the second hinge. A center of the third pinion is fixed to ashaft which is fixed to the other of the hinge pieces of the secondhinge. Teeth of the second pinion and teeth of the third pinion engagewith each other through the intermediate gear. A center of theintermediate gear is fixed to the shaft which is fixed to the one of thehinge pieces of the second hinge. A second slide function is provided inthe one of the hinge pieces of the second hinge. The second hinge isprovided over the second substrate and the third substrate so that teethof the second rack and teeth of the second pinion engage with each otherin a state where the side of the second substrate which is opposite tothe side of the second substrate to which the first hinge is fixed isadjacent to the side of the corner of the third substrate to which thesecond rack is fixed. The third substrate and the one of the hingepieces of the second hinge are fixed to each other in a state where thethird substrate can be moved in a horizontal direction with the secondslide function while being overlapped with the one of the hinge piecesof the second hinge. The second substrate and the other of the hingepieces of the second hinge are fixed to each other. When the firstsubstrate is moved, a rotational force of the first pinion istransmitted to the first rack, and thus the second substrate is moved inthe horizontal direction while being overlapped with the other of thehinge pieces of the first hinge. When the second substrate is moved, arotational force of the third pinion is transmitted to the second rackthrough the intermediate gear and the second pinion, and thus the thirdsubstrate is moved in the horizontal direction while being overlappedwith the one of the hinge pieces of the second hinge.

One flexible component can be fixed to the support of the flexiblecomponent across the first substrate, the second substrate, and thethird substrate, and bending operation can be performed without breakingthe flexible component.

The first substrate and the second substrate can be connected to eachother with two sets of the first hinge and peripheral components (afirst rack, a first pinion, and the like), and the second substrate andthe third substrate can be connected to each other with two sets of thesecond hinge and peripheral components (a second rack, a second pinion,a third pinion, and the like).

According to another embodiment of the present invention, alight-emitting device includes a first substrate, a second substrate, arack, a pinion, a hinge, and a flexible light-emitting device. The rackis fixed to a corner of the first substrate. A center of the pinion isfixed to a shaft of the hinge. A slide function is provided in one ofhinge pieces of the hinge. The shaft of the hinge is fixed to the otherof the hinge pieces of the hinge. The hinge is provided over the firstsubstrate and the second substrate so that teeth of the rack and teethof the pinion engage with each other in a state where the secondsubstrate is adjacent to the side of the corner of the first substrateto which the rack is fixed. The first substrate and the one of the hingepieces of the hinge are fixed to each other in a state where the firstsubstrate can be moved in a horizontal direction with the slide functionwhile being overlapped with the one of the hinge pieces of the hinge.The second substrate and the other of the hinge pieces of the hinge arefixed to each other. The flexible light-emitting device is fixed acrossthe first substrate and the second substrate. When the second substrateis moved, a rotational force of the pinion is transmitted to the rack,and thus the first substrate is moved in the horizontal direction whilebeing overlapped with the one of the hinge pieces of the hinge.

According to another embodiment of the present invention, alight-emitting device includes a first substrate, a second substrate, athird substrate, a first rack, a second rack, a first pinion, a secondpinion, a third pinion, an intermediate gear, a first hinge, a secondhinge, and a flexible light-emitting device. The first rack is fixed toa corner of the second substrate. A center of the first pinion is fixedto a shaft of the first hinge. A shaft of the first hinge is fixed toone of hinge pieces of the first hinge. A first slide function isprovided in the other of the hinge pieces of the first hinge. The firsthinge is provided over the first substrate and the second substrate sothat teeth of the first rack and teeth of the second pinion engage witheach other in a state where the first substrate is adjacent to the sideof the corner of the second substrate to which the first rack is fixed.The second substrate and the other of the hinge pieces of the firsthinge are fixed to each other in a state where the second substrate canbe moved in a horizontal direction with the first slide function whilebeing overlapped with the other of the hinge pieces of the first hinge.The first substrate and the one of the hinge pieces of the first hingeare fixed to each other. The second rack is fixed to a corner of thethird substrate. A center of the second pinion is fixed to a shaft whichis fixed to one of hinge pieces of the second hinge. A center of thethird pinion is fixed to a shaft which is fixed to the other of thehinge pieces of the second hinge. Teeth of the second pinion and teethof the third pinion engage with each other through the intermediategear. A center of the intermediate gear is fixed to the shaft which isfixed to the one of the hinge pieces of the second hinge. A second slidefunction is provided in the one of the hinge pieces of the second hinge.The second hinge is provided over the second substrate and the thirdsubstrate so that teeth of the second rack and teeth of the secondpinion engage with each other in a state where the side of the secondsubstrate which is opposite to the side of the second substrate to whichthe first hinge is fixed is adjacent to the side of the corner of thethird substrate to which the second rack is fixed. The third substrateand the one of the hinge pieces of the second hinge are fixed to eachother in a state where the third substrate can be moved in a horizontaldirection with the second slide function while being overlapped with theone of the hinge pieces of the second hinge. The second substrate andthe other of the hinge pieces of the second hinge are fixed to eachother. The flexible light-emitting device is fixed across the firstsubstrate, the second substrate, and the third substrate. When the firstsubstrate is moved, a rotational force of the first pinion istransmitted to the first rack, and thus the second substrate is moved inthe horizontal direction while being overlapped with the other of thehinge pieces of the first hinge. When the second substrate is moved, arotational force of the third pinion is transmitted to the second rackthrough the intermediate gear and the second pinion, and thus the thirdsubstrate is moved in the horizontal direction while being overlappedwith the one of the hinge pieces of the second hinge.

As the flexible light-emitting device, a display device or a lightingdevice using an organic EL element can be used.

According to one embodiment of the present invention, a support forsupporting a flexible component can be provided. A support forperforming bending operation without decreasing the reliability of aflexible component can be provided. A support for maintaining theallowable curvature radius of a flexible component can be provided. Asupport for improving the reliability of a flexible component can beprovided. A support for suppressing a decrease in electricalcharacteristics of a flexible component can be provided. A novel supportof a flexible component can be provided. A novel light-emitting devicecan be provided.

Note that the description of these effects does not disturb theexistence of other effects. In one embodiment of the present invention,there is no need to achieve all the effects. Other objects will beapparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view illustrating a support for supporting aflexible component;

FIGS. 2A to 2D are a top view and cross-sectional views illustrating asupport for supporting a flexible component;

FIGS. 3A to 3D are a top view and cross-sectional views illustrating asupport for supporting a flexible component:

FIGS. 4A to 4C are cross-sectional views illustrating a support forsupporting a flexible component;

FIGS. 5A to 5C are cross-sectional views illustrating a support forsupporting a flexible component;

FIGS. 6A and 6B are perspective views illustrating a support forsupporting a flexible component:

FIGS. 7A to 7D are a top view and cross-sectional views illustrating asupport for supporting a flexible component:

FIGS. 8A to 8D are a top view and cross-sectional views illustrating asupport for supporting a flexible component;

FIGS. 9A to 9D are cross-sectional views illustrating a support forsupporting a flexible component;

FIGS. 10A and 10B illustrate a light-emitting panel;

FIGS. 11A and 11B each illustrate a light-emitting panel;

FIGS. 12A and 12B each illustrate a light-emitting panel;

FIGS. 13A and 13B each illustrate a light-emitting panel;

FIGS. 14A to 14C illustrate a method for manufacturing a light-emittingpanel:

FIGS. 15A to 15C illustrate a method for manufacturing a light-emittingpanel; and

FIGS. 16A and 16B illustrate gears.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Therefore, the present invention shouldnot be construed as being limited to the description in the followingembodiments. Note that in the structures of the invention describedbelow, the same portions or portions having similar functions aredenoted by the same reference numerals in different drawings, anddescription of such portions is not repeated in some cases.

Embodiment 1

In this embodiment, a support of a flexible component of one embodimentof the present invention is described. The support of one embodiment ofthe present invention can be used for general components with lowresistance to bending, and the components are not limited to electricalcomponents.

FIG. 1 is a perspective view of a support of a flexible component of oneembodiment of the present invention which can be opened and closed, in astate where the flexible component is opened so that a hinge forms anobtuse angle. FIGS. 2A to 2D illustrate a state where the support isopened so that the flexible component is flat. FIG. 2A is a top view (ofa side on which the flexible component is provided), FIG. 2B is across-sectional view taken along line A1-A2 in FIG. 2A, FIG. 2C is across-sectional view taken along line A3-A4 in FIG. 2A, and FIG. 2D is across-sectional view taken along line A5-A6 in FIG. 2A.

The support of the flexible component of one embodiment of the presentinvention includes a first substrate 110, a second substrate 120, ahinge 130, a rack 150, and a pinion 160. FIG. 2A illustrates a structurein which the first substrate 110 and the second substrate 120 areconnected to each other with two hinges which are provided to beline-symmetric with respect to the line A1-A2 (a center line dividingthe drawing to an upper part and a lower part). The two hinges are thesame except being mirror images. Thus, the description of only one ofthe hinges and the like is made below.

The rack 150 is fixed to a corner of the first substrate 110, and thecenter of the pinion 160 is fixed to a shaft 140 of the hinge 130.Furthermore, the shaft 140 is fixed to a hinge piece 132 of the hinge130. In other words, the operation of the hinge piece 132 is transmittedto the pinion 160 through the shaft 140.

In a state where the second substrate 120 is adjacent to the side of thecorner of the first substrate 110 to which the rack 150 is fixed, thehinge 130 is placed over the first substrate 110 and the secondsubstrate 120 so that teeth of the rack 150 and teeth of the pinion 160engage with each other (see FIG. 2D).

A slide function is provided in a hinge piece 131 of the hinge 130, andwith the slide function, the first substrate 110 and the hinge piece 131of the hinge 130 are fixed to each other in a state where the firstsubstrate 110 can be moved in the horizontal direction while beingoverlapped with the hinge piece 131 of the hinge 130 (see FIG. 2C).Furthermore, the second substrate 120 and the hinge piece 132 of thehinge 130 are fixed to each other.

In one embodiment of the present invention, there is no limitation onthe structure of the slide function. For example, as illustrated in thedrawings, the slide function can be formed using slotted holes 170 inthe hinge piece 131 of the hinge 130 and jigs 180 (e.g., screws)inserted to the slotted holes and fixed to the first substrate. Theslotted holes may be formed on the first substrate side. In addition, asthe slide function, a function in which upper and lower tables areoverlapped with each other with a bearing, a low friction material, orthe like provided therebetween can be used.

Although two slotted holes 170 are provided in the hinge piece 131 ofthe hinge 130 here, one slotted hole 170 may be provided.

The flexible component 190 in regions other than a region F1 illustratedin FIGS. 2A and 2B can be fixed to the first substrate 110 and thesecond substrate 120. The region F1 corresponds to a bendable region ofthe flexible component 190, and it is necessary that the first substrate110 and the flexible component 190 are not fixed to each other in theregion F1.

FIGS. 3A to 3D illustrate a state where the support illustrated in FIG.1 is closed. FIG. 3A is a top view. FIG. 3B is a cross-sectional viewtaken along line B1-B2 in FIG. 3A, FIG. 3C is a cross-sectional viewtaken along line B3-B4 in FIG. 3A, and FIG. 3D is a cross-sectional viewtaken along line B5-B6 in FIG. 3A.

When the second substrate 120 is moved in the support having the abovestructure, the rotational force of the pinion 160 is transmitted to therack 150, and the first substrate 110 can be moved in the horizontaldirection while being overlapped with the hinge piece 131 of the hinge130. The same operation can be performed also in such a manner that thefirst substrate 110 is moved or both of the substrates are moved.

Thus, even when the flexible component 190 is fixed to the firstsubstrate 110 and the second substrate 120 as illustrated in FIG. 2B,the support can be bent while the curvature radius of the bendableportion is kept constant as illustrated in FIG. 3B. Note that theallowable curvature radius of the bendable portion of the flexiblecomponent 190 can be adjusted by selecting the diameter of a tubecovering the shaft 140 of the hinge 130 and the diameter of the pinion160.

FIGS. 4A to 4C are side views illustrating a state of the support of oneembodiment of the present invention from closed to opened. Here, when anend of the flexible component 190 on the first substrate 110 side isreferred to as E1 and an end of the flexible component 190 on the secondsubstrate 120 side is referred to as E2, the positions of the ends E1and E2 are not changed due to opening and closing of the support.

In other words, in the support of one embodiment of the presentinvention, the flexible component 190 other than the bendable portioncan be fixed to the first substrate 110 and the second substrate 120.Thus, the flexible component 190 can have high mechanical strength, andthus the reliability can be improved. The surface shapes of the firstsubstrate 110 and the second substrate 120 can be reflected in theflexible component 190; thus, the function or design can be improved.For example, in the case where the flexible component 190 is a displaydevice and the surface shapes of the first substrate 110 and the secondsubstrate 120 are flat, the visibility can be improved.

As a reference example, FIGS. 5A to 5C illustrate a state of a supportwhich is not one embodiment of the present invention from closed toopened. FIGS. 5A to 5C are side views illustrating states of the supportfrom closed to opened. The support illustrated in FIGS. 5A to 5C doesnot include a rack, a pinion, and a slide function, and is differentfrom the one embodiment of the present invention in that the firstsubstrate 110 cannot be moved in the horizontal direction.

In the support illustrated in FIGS. 5A to 5C, the flexible component 190is fixed to the first substrate 110, not to the second substrate 120.Here, in opening and closing of the support, the position of the end E1of the flexible component 190 is not changed; on the other hand, theposition of the end E2 of the flexible component 190 is changedaccording to the degree of opening and closing of the support.

This is because a region 191 which is part of the flexible component 190is used as a bendable portion as illustrated in FIG. 5A. When thesupport is changed from the state in FIG. 5B to that in FIG. 5A, theflexible component 190 is moved over the second substrate 120 to bepulled in the hinge direction, and thus the position of the end E2 ofthe flexible component 190 is changed. When the support is changed fromthe state in FIG. 5B to that in FIG. 5C, the flexible component 190 ismoved over the second substrate 120 in a direction opposite to the hingedirection, and thus the position of the end E2 of the flexible component190 is changed.

Since the flexible component 190 cannot be fixed to the second substrate120 in the support illustrated in FIGS. 5A to 5C, it is difficult toimprove the mechanical strength. Friction is caused between the secondsubstrate 120 and the flexible component; thus, the mechanical orelectrical reliability is decreased in some cases. Furthermore, sincethe surface shape of the second substrate 120 cannot be reflected in theflexible component 190, it is difficult to improve the function anddesign sufficiently.

Thus, according to one embodiment of the present invention, a flexiblecomponent with excellent reliability, function, and design can beprovided.

Note that components such as a gear or a hinge described in thisspecification are merely examples, and the shapes, numbers, and the likethereof are not limited. Other components having functions similar tothose of the gear and the hinge described in this specification may beused instead thereof.

This embodiment can be implemented in an appropriate combination withany of the structures described in the other embodiments.

Embodiment 2

In this embodiment, a support of a flexible component of one embodimentof the present invention, which is different from Embodiment 1, isdescribed. Although the double-fold support is described in Embodiment1, a triple-fold support is described in this embodiment.

FIGS. 6A and 6B are perspective views of the support of the flexiblecomponent of one embodiment of the present invention that can be openedand closed when the support is opened in a state where each hinge formsan obtuse angle. FIG. 6A illustrates the side on which the flexiblecomponent is provided, and FIG. 6B illustrates the opposite side of FIG.6A. FIGS. 7A to 7D illustrate a state where the support of the flexiblecomponent of one embodiment of the present invention that can be openedand closed. FIG. 7A is a top view (of a side on which the flexiblecomponent is provided), FIG. 7B is a cross-sectional view taken alongline C1-C2 in FIG. 7A, FIG. 7C is a cross-sectional view taken alongline C3-C4 in FIG. 7A, and FIG. 7D is a cross-sectional view taken alongline C5-C6 in FIG. 7A.

The support of the flexible component of one embodiment of the presentinvention includes a first substrate 211, a second substrate 212, athird substrate 213, a first hinge 220, a first rack 251, a second rack252, a first pinion 261, a second pinion 262, a third pinion 263, and anintermediate gear 264. FIG. 7A illustrates a structure in which thefirst substrate 211, the second substrate 212, and the third substrate213 are connected with two pairs of hinges (four hinges in total) whichare provided to be line-symmetric with respect to the line C1-C2 (acenter line dividing the drawing to an upper part and a lower part). Thetwo hinges which connect the first substrate 211 and the secondsubstrate 212 are the same except being mirror images. Furthermore, thetwo hinges which connect the second substrate 212 and the thirdsubstrate 213 are the same except being mirror images. Thus, thedescription of only one of the hinges which are the same is made below.

The first rack 251 is fixed to a corner of the second substrate 212, andthe center of the first pinion 261 is fixed to a shaft 241 of the firsthinge 220. The shaft 241 is fixed to a hinge piece 221 of the firsthinge 220. In other words, the operation of the hinge piece 221 istransmitted to the first pinion 261 through the shaft 241.

In a state where the first substrate 211 is adjacent to the side of thecorner of the second substrate 212 to which the first rack 251 is fixed,the first hinge 220 is placed over the first substrate 211 and thesecond substrate 212 so that teeth of the first rack 251 and teeth ofthe first pinion 261 engage with each other (see FIG. 7D).

A first slide function is provided in a hinge piece 222 of the firsthinge 220, and with the first slide function, the second substrate 212and the hinge piece 222 of the first hinge 220 are fixed to each otherin a state where the second substrate 212 can be moved in the horizontaldirection while being overlapped with the hinge piece 222 of the firsthinge 220 (see FIG. 7C). Furthermore, the first substrate 211 and thehinge piece 221 of the first hinge 220 are fixed to each other.

In one embodiment of the present invention, there is no limitation onthe structure of the first slide function. For example, as illustratedin the drawings, slotted holes 271 are formed in the hinge piece 222 ofthe first hinge 220, and can be formed using jigs 280 (e.g., screws)inserted into the slotted holes. Note that the description of the slidefunction in Embodiment 1 can be referred to for the first slidefunction.

Although two slotted holes 271 are provided in the hinge piece 222 ofthe first hinge 220 here, one slotted hole 271 may be provided.

A flexible component 290 in regions other than a region F2 illustratedin FIGS. 7A and 7B can be fixed to the first substrate 211, the secondsubstrate 212, and the third substrate 213. The region F2 corresponds toa bendable region of the flexible component 290, and it is necessarythat the second substrate 212 and the flexible component 290 are notfixed to each other in the region F2.

The second rack 252 is fixed to a corner of the third substrate 213, andthe center of the second pinion 262 is fixed to a shaft 242 fixed to thehinge piece 232 of the second hinge 230. The center of the third pinion263 is fixed to a shaft 243 fixed to the hinge piece 231 of the secondhinge 230. The second pinion 262 and the third pinion 263 engage witheach other through the intermediate gear 264. The center of theintermediate gear is fixed to a shaft fixed to the hinge piece 232 ofthe second hinge 230. With such a structure, the operation of the hingepiece 231 is transmitted to the third pinion 263 through the shaft 243,and the operation of the third pinion 263 is transmitted to the secondpinion 262 through an intermediate gear 244.

In a state where the side of the second substrate 212 to which the firsthinge 220 is fixed is adjacent to the side of the corner of the thirdsubstrate 213 to which the second rack 252 is fixed, the second hinge230 is placed over the second substrate 212 and the third substrate 213so that teeth of the second rack 252 and teeth of the second pinion 262engage with each other (see FIG. 7D).

A second slide function is provided in the hinge piece 232 of the secondhinge 230, and the third substrate 213 and the hinge piece 232 of thesecond hinge 230 are fixed to each other in a state where the thirdsubstrate 213 can be moved in the horizontal direction while beingoverlapped with the hinge piece 232 of the second hinge 230 (see FIG.7C). Furthermore, the second substrate 212 and the hinge piece 231 ofthe second hinge 230 are fixed to each other.

In one embodiment of the present invention, there is no limitation onthe structure of the second slide function. For example, as illustratedin the drawings, slotted holes 272 are formed in the hinge piece 232 ofthe second hinge 230, and can be formed using the jigs 280 (e.g.,screws) inserted into the slotted holes. Note that the description ofthe slide function in Embodiment 1 can be referred to for the secondslide function.

Although one slotted hole 272 is provided in the hinge piece 232 of thesecond hinge 230 here, two slotted holes 272 may be provided.

A fourth substrate 214 is fixed to the third substrate 213. Actually,the flexible component 290 is fixed to the fourth substrate 214. Notethat if the third substrate 213 and the fourth substrate 214 areregarded as one substrate, the description can be made assuming that theflexible component 290 is fixed to the third substrate 213.

Furthermore, the corner of the second substrate 212 is partly removed sothat when the flexible component is folded, the second pinion 262, thethird pinion 263, and the intermediate gear 264 do not interfere witheach other.

Although FIGS. 7A to 7D illustrate the structure in which the hingepiece 231 of the second hinge 230 is formed in the second substrate 212,the structure in which the hinge piece 231 is fixed to the secondsubstrate 212 as described above may be employed.

Alternatively, the second pinion 262, the third pinion 263, and theintermediate gear 264 may have a structure illustrated in FIGS. 16A and16B. FIG. 16A is a top view and FIG. 16B is a cross-sectional view.

The third pinion 263 includes a gear 263 a and a gear 263 b. The secondpinion 262 and the gear 263 b engage with each other through theintermediate gear 264. Furthermore, the second rack 252 engages withonly the gear 263 a.

FIGS. 8A to 8D illustrate a state where the support illustrated in FIGS.6A and 6B is closed. FIG. 8A is a top view, FIG. 8B is a cross-sectionalview taken along line D1-D2 in FIG. 8A. FIG. 8C is a cross-sectionalview taken along line D3-D4 in FIG. 8A, and FIG. 8D is a cross-sectionalview taken along line D5-D6 in FIG. 8A.

When the first substrate 211 is moved in the support having the abovestructure, the rotational force of the first pinion 261 is transmittedto the first rack 251, and the second substrate 212 can be moved in thehorizontal direction while being overlapped with the hinge piece 222 ofthe first hinge 220.

When the second substrate 212 is moved, the rotational force of thethird pinion 263 is transmitted to the second rack 252 through theintermediate gear 264 and the second pinion 262, and the third substrate213 can be moved in the horizontal direction while being overlapped withthe hinge piece 232 of the second hinge 230. Note that moving thesubstrate corresponds to opening and closing of the support, and theopening and closing of the support can be performed by moving either ofthe substrates.

Thus, even in a state where the flexible component 290 is fixed to thefirst substrate 211, the second substrate 212, and the third substrate213 (the fourth substrate 214) as illustrated in FIG. 7B, the supportcan be bent as illustrated in FIG. 8B while keeping the curvature radiusof the bendable portion. The allowable curvature radius of the bendableportion of the flexible component 290 can be adjusted by selecting thediameter of a tube covering the shaft 241 of the first hinge 220, thediameter of the first pinion 261, the diameter of a tube covering theshaft 243 of the second hinge 230, and the diameter of the third pinion263.

FIGS. 9A to 9D are side views illustrating a state of a support of oneembodiment of the present invention from closed to opened. Note thatpart of the third substrate 213 is seen transparently in FIGS. 9A to 9D.Here, when an end of the flexible component 290 on the first substrate211 side is referred to as E1 and an end of the flexible component 290on the third substrate 213 side is referred to as E2, the positions ofthe ends E1 and E2 are not changed due to opening and closing of thesupport.

In other words, in the support of one embodiment of the presentinvention, the flexible component 290 is fixed to the first substrate211, the second substrate 212, and the third substrate 213 (the fourthsubstrate 214); thus, the flexible component 290 can have highmechanical strength, and thus the reliability can be improved.Furthermore, the surface shapes of the first substrate 211, the secondsubstrate 212, and the third substrate 213 (the fourth substrate 214)can be reflected in the flexible component 290; thus, the function anddesign can be improved. For example, in the case where the flexiblecomponent 290 is a display device and the surface shapes of the firstsubstrate 211, the second substrate 212, and the third substrate 213(the fourth substrate 214) are flat, the visibility can be improved.

Thus, according to one embodiment of the present invention, a flexiblecomponent with excellent reliability, function, and design can beprovided. In addition, according to one embodiment of the presentinvention, the flexible component can be folded small, and thus can haveexcellent portability.

This embodiment can be implemented in an appropriate combination withany of the structures described in the other embodiments.

Embodiment 3

In this embodiment, examples of a light-emitting device (light-emittingpanel) which can be used as the flexible components described inEmbodiments I and 2 are described.

Specific Example 1

FIG. 10A is a plan view of the light-emitting panel which can be used asan example of the flexible component, and FIG. 10B is an example of across-sectional view taken along dashed-dotted line G1-G2 in FIG. 10A.

The light-emitting panel shown in FIG. 10B includes an element layer301, a bonding layer 305, and a substrate 303. The element layer 301includes a substrate 401, a bonding layer 403, an insulating layer 405,a transistor 440, a conductive layer 357, an insulating layer 407, aninsulating layer 409, a light-emitting element 430, an insulating layer411, a sealing layer 413, an insulating layer 461, a coloring layer 459,a light-blocking layer 457, and an insulating layer 455.

The conductive layer 357 is electrically connected to an FPC 308 via aconnector 415.

A light-emitting element 430 includes a lower electrode 431, an EL layer433, and an upper electrode 435. The lower electrode 431 is electricallyconnected to a source electrode or a drain electrode of a transistor440. An end portion of the lower electrode 431 is covered with theinsulating layer 411. The light-emitting element 430 has a top emissionstructure. The upper electrode 435 has a light-transmitting property andtransmits light emitted from the EL layer 433.

The coloring layer 459 is provided to overlap with the light-emittingelement 430, and the light-blocking layer 457 is provided to overlapwith the insulating layer 411. The coloring layer 459 and thelight-blocking layer 457 are covered with the insulating layer 461. Thespace between the light-emitting element 430 and the insulating layer461 is filled with the sealing layer 413.

The light-emitting panel includes a plurality of transistors in a lightextraction portion 304 and a driver circuit portion 306. The transistor440 is provided over the insulating layer 405. The insulating layer 405and the substrate 401 are attached to each other with the bonding layer403. The insulating layer 455 and the substrate 303 are attached to eachother with the bonding layer 305. It is preferable to use films with lowwater permeability for the insulating layer 405 and the insulating layer455, in which case an impurity such as water can be prevented fromentering the light-emitting element 430 or the transistor 440, leadingto improved reliability of the light-emitting panel. The bonding layer403 can be formed using a material similar to that of the bonding layer305.

The light-emitting panel in Specific Example 1 can be manufactured inthe following manner: the insulating layer 405, the transistor 440, andthe light-emitting element 430 are formed over a formation substratewith high heat resistance; the formation substrate is separated; and theinsulating layer 405, the transistor 440, and the light-emitting element430 are transferred to the substrate 401 and attached thereto with thebonding layer 403. The light-emitting panel in Specific Example 1 can bemanufactured in the following manner: the insulating layer 455, thecoloring layer 459, and the light-blocking layer 457 are formed over aformation substrate with high heat resistance; the formation substrateis separated; and the insulating layer 455, the coloring layer 459, andthe light-blocking layer 457 are transferred to the substrate 303 andattached thereto with the bonding layer 305.

In the case where a material with high water permeability and low heatresistance (e.g., resin) is used for a substrate, it is impossible toexpose the substrate to high temperature in the manufacturing process.Thus, there is a limitation on conditions for forming a transistor andan insulating film over the substrate. In the manufacturing method ofthis embodiment, a transistor and the like can be formed over aformation substrate having high heat resistance; thus, a highly reliabletransistor and an insulating film with sufficiently low waterpermeability can be formed. Then, the transistor and the insulating filmare transferred to the substrate 303 or the substrate 401, whereby ahighly reliable light-emitting panel can be manufactured. Thus, with oneembodiment of the present invention, a thin or/and lightweightlight-emitting device with high reliability can be provided. Details ofthe manufacturing method will be described later.

The substrate 303 and the substrate 401 are each preferably formed usinga material with high toughness. Thus, a display device with high impactresistance that is less likely to be broken can be provided. Forexample, when the substrate 303 is an organic resin substrate and thesubstrate 401 is a substrate formed using a thin metal material or athin alloy material, a light-emitting panel that is more lightweight andless likely to be broken as compared with the case where a glasssubstrate is used can be provided.

A metal material and an alloy material, which have high thermalconductivity, are preferred because they can easily conduct heat to thewhole substrate and accordingly can prevent a local temperature rise inthe light-emitting panel. The thickness of a substrate using a metalmaterial or an alloy material is preferably greater than or equal to 10μm and less than or equal to 200 μm, further preferably greater than orequal to 20 μm and less than or equal to 50 μm.

Further, when a material with high thermal emissivity is used for thesubstrate 401, the surface temperature of the light-emitting panel canbe prevented from rising, leading to prevention of breakage or adecrease in reliability of the light-emitting panel. For example, thesubstrate 401 may have a stacked structure of a metal substrate and alayer with high thermal emissivity (the layer can be formed using ametal oxide or a ceramic material, for example).

Specific Example 2

FIG. 11A shows another example of the light extraction portion 304 inthe light-emitting panel. The light-emitting panel shown in FIG. 11A iscapable of touch operation. In the following specific examples,description of components similar to those in Specific Example 1 isomitted.

The light-emitting panel shown in FIG. 11A includes the element layer301, the bonding layer 305, and the substrate 303. The element layer 301includes the substrate 401, the bonding layer 403, the insulating layer405, the transistor 440, the insulating layer 407, the insulating layer409, the light-emitting element 430, the insulating layer 411, aninsulating layer 417, the sealing layer 413, the insulating layer 461,the coloring layer 459, the light-blocking layer 457, a light-receivingelement, a conductive layer 481, a conductive layer 483, an insulatinglayer 491, an insulating layer 493, an insulating layer 495, and theinsulating layer 455.

Specific Example 2 includes the insulating layer 417 over the insulatinglayer 411. The space between the substrate 303 and the substrate 401 canbe adjusted with the insulating layer 417.

FIG. 11A shows an example in which a light-receiving element is providedbetween the insulating layer 455 and the sealing layer 413. Since thelight-receiving element can be placed to overlap with anon-light-emitting region (e.g., a region where the transistor 440 or awiring is provided) on the substrate 401 side, the light-emitting panelcan be provided with a touch sensor without a decrease in the apertureratio of a pixel (light-emitting element).

As the light-receiving element included in the light-emitting panel, forexample, a pn photodiode or a pin photodiode can be used. In thisembodiment, a pin photodiode including a p-type semiconductor layer 471,an i-type semiconductor layer 473, and an n-type semiconductor layer 475is used as the light-receiving element.

Note that the i-type semiconductor layer 473 is a semiconductor in whichthe concentration of each of an impurity imparting p-type conductivityand an impurity imparting n-type conductivity is 1×10²⁰ cm⁻³ or less andwhich has photoconductivity 100 times or more as high as darkconductivity. The i-type semiconductor layer 473 also includes, in itscategory, a semiconductor that contains an impurity element belonging toGroup 13 or Group 15 of the periodic table. In other words, since ani-type semiconductor has weak n-type electric conductivity when animpurity element for controlling valence electrons is not addedintentionally, the i-type semiconductor layer 473 includes, in itscategory, a semiconductor to which an impurity element imparting p-typeconductivity is added intentionally or unintentionally at the time ofdeposition or after the deposition.

The light-blocking layer 457 is closer to the substrate 303 than thelight-receiving element is, and overlaps with the light-receivingelement. The light-blocking layer 457 between the light-receivingelement and the sealing layer 413 can prevent the light-receivingelement from being irradiated with light emitted from the light-emittingelement 430.

The conductive layer 481 and the conductive layer 483 are electricallyconnected to the light-receiving element. The conductive layer 481preferably transmits light incident on the light-receiving element. Theconductive layer 483 preferably blocks light incident on thelight-receiving element.

It is preferable to provide an optical touch sensor between thesubstrate 303 and the sealing layer 413 because the optical touch sensoris less likely to be affected by light emitted from the light-emittingelement 430 and can have improved S/N ratio.

Specific Example 3

FIG. 11B shows another example of the light extraction portion 304 inthe light-emitting panel. The light-emitting panel shown in FIG. 11B iscapable of touch operation.

The light-emitting panel shown in FIG. 11B includes the element layer301, the bonding layer 305, and the substrate 303. The element layer 301includes the substrate 401, the bonding layer 403, the insulating layer405, the transistor 440, the insulating layer 407, an insulating layer409 a, an insulating layer 409 b, the light-emitting element 430, theinsulating layer 411, the insulating layer 417, the sealing layer 413,the coloring layer 459, the light-blocking layer 457, a light-receivingelement, a conductive layer 480, the conductive layer 481, and theinsulating layer 455.

FIG. 11B shows an example in which a light-receiving element is providedbetween the insulating layer 405 and the sealing layer 413. Since thelight-receiving element is provided between the insulating layer 405 andthe sealing layer 413, a conductive layer to which the light-receivingelement is electrically connected and a photoelectric conversion layerincluded in the light-receiving element can be formed using the samematerials and the same steps as a conductive layer and a semiconductorlayer included in the transistor 440. Thus, the light-emitting panelcapable of touch operation can be manufactured without a significantincrease in the number of manufacturing steps.

Specific Example 4

FIG. 12A shows another example of the light-emitting panel. Thelight-emitting panel shown in FIG. 12A is capable of touch operation.

The light-emitting device shown in FIG. 12A includes the element layer301, the bonding layer 305, and the substrate 303. The element layer 301includes the substrate 401, the bonding layer 403, the insulating layer405, the transistor 440, a conductive layer 356, the conductive layer357, the insulating layer 407, the insulating layer 409, thelight-emitting element 430, the insulating layer 411, the insulatinglayer 417, the sealing layer 413, the coloring layer 459, thelight-blocking layer 457, the insulating layer 455, a conductive layer472, a conductive layer 474, an insulating layer 476, an insulatinglayer 478, a conductive layer 494, and a conductive layer 496.

FIG. 12A shows an example in which a capacitive touch sensor is providedbetween the insulating layer 455 and the sealing layer 413. Thecapacitive touch sensor includes the conductive layer 472 and theconductive layer 474.

The conductive layer 356 and the conductive layer 357 are electricallyconnected to the FPC 308 via the connector 415. The conductive layer 494and the conductive layer 496 are electrically connected to theconductive layer 474 via conductive particles 492. Thus, the capacitivetouch sensor can be driven via the FPC 308.

Specific Example 5

FIG. 12B shows another example of the light-emitting panel. Thelight-emitting panel shown in FIG. 12B is capable of touch operation.

The light-emitting panel shown in FIG. 12B includes the element layer301, the bonding layer 305, and the substrate 303. The element layer 301includes the substrate 401, the bonding layer 403, the insulating layer405, the transistor 440, the conductive layer 356, the conductive layer357, the insulating layer 407, the insulating layer 409, thelight-emitting element 430, the insulating layer 411, the insulatinglayer 417, the sealing layer 413, the coloring layer 459, thelight-blocking layer 457, the insulating layer 455, a conductive layer470, the conductive layer 472, the conductive layer 474, the insulatinglayer 476, and the insulating layer 478.

FIG. 12B shows an example in which a capacitive touch sensor is providedbetween the insulating layer 455 and the sealing layer 413. Thecapacitive touch sensor includes the conductive layer 472 and theconductive layer 474.

The conductive layer 356 and the conductive layer 357 are electricallyconnected to an FPC 308 a via a connector 415 a. The conductive layer470 is electrically connected to an FPC 308 b via a connector 415 b.Thus, the light-emitting element 430 and the transistor 440 can bedriven via the FPC 308 a, and the capacitive touch sensor can be drivenvia the FPC 308 b.

Specific Example 6

FIG. 13A shows another example of the light extraction portion 304 inthe light-emitting panel.

The light extraction portion 304 shown in FIG. 13A includes thesubstrate 303, the bonding layer 305, a substrate 402, the insulatinglayer 405, the transistor 440, the insulating layer 407, a conductivelayer 408, the insulating layer 409 a, the insulating layer 409 b, thelight-emitting element 430, the insulating layer 411, the sealing layer413, and the coloring layer 459.

The light-emitting element 430 includes the lower electrode 431, the ELlayer 433, and the upper electrode 435. The lower electrode 431 iselectrically connected to the source electrode or the drain electrode ofthe transistor 440 via the conductive layer 408. An end portion of thelower electrode 431 is covered with the insulating layer 411. Thelight-emitting element 430 has a bottom emission structure. The lowerelectrode 431 has a light-transmitting property and transmits lightemitted from the EL layer 433.

The coloring layer 459 is provided to overlap with the light-emittingelement 430, and light emitted from the light-emitting element 430 isextracted from the substrate 303 side through the coloring layer 459.The space between the light-emitting element 430 and the substrate 402is filled with the sealing layer 413. The substrate 402 can be formedusing a material similar to that of the substrate 401.

Specific Example 7

FIG. 13B shows another example of the light-emitting panel.

The light-emitting panel shown in FIG. 13B includes the element layer301, the bonding layer 305, and the substrate 303. The element layer 301includes the substrate 402, the insulating layer 405, a conductive layer510 a, a conductive layer 510 b, a plurality of light-emitting elements,the insulating layer 411, a conductive layer 412, and the sealing layer413.

The conductive layer 510 a and the conductive layer 510 b, which areexternal connection electrodes of the light-emitting panel, can each beelectrically connected to an FPC or the like.

The light-emitting element 430 includes the lower electrode 431, the ELlayer 433, and the upper electrode 435. An end portion of the lowerelectrode 431 is covered with the insulating layer 411. Thelight-emitting element 430 has a bottom emission structure. The lowerelectrode 431 has a light-transmitting property and transmits lightemitted from the EL layer 433. The conductive layer 412 is electricallyconnected to the lower electrode 431.

The substrate 303 may have, as a light extraction structure, ahemispherical lens, a micro lens array, a film provided with an unevensurface structure, a light diffusing film, or the like. For example, alight extraction structure can be formed by attaching the above lens orfilm to a resin substrate with an adhesive or the like havingsubstantially the same refractive index as the substrate or the lens orfilm.

The conductive layer 412 is preferably, though not necessarily, providedbecause voltage drop due to the resistance of the lower electrode 431can be prevented. In addition, for a similar purpose, a conductive layerelectrically connected to the upper electrode 435 may be provided overthe insulating layer 411.

The conductive layer 412 can be a single layer or a stacked layer formedusing a material selected from copper, titanium, tantalum, tungsten,molybdenum, chromium, neodymium, scandium, nickel, or aluminum, an alloymaterial containing any of these materials as its main component, or thelike. The thickness of the conductive layer 412 can be greater than orequal to 0.1 μm and less than or equal to 3 μm, preferably greater thanor equal to 0.1 μm and less than or equal to 0.5 μm.

When a paste (e.g., silver paste) is used as a material for theconductive layer electrically connected to the upper electrode 435,metal particles forming the conductive layer aggregate; therefore, thesurface of the conductive layer is rough and has many gaps. Thus, it isdifficult for the EL layer 433 to completely cover the conductive layer;accordingly, the upper electrode and the conductive layer areelectrically connected to each other easily, which is preferable.

Examples of Materials

Next, materials and the like that can be used for the light-emittingpanel are described. Note that description of the components alreadydescribed in this embodiment is omitted.

The element layer 301 includes at least a light-emitting element. As thelight-emitting element, a self-luminous element can be used, and anelement whose luminance is controlled by current or voltage is includedin the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, an inorganic ELelement, or the like can be used.

The element layer 301 may further include a transistor for driving thelight-emitting element, a touch sensor, or the like.

The structure of the transistors in the light-emitting panel is notparticularly limited. For example, a forward staggered transistor or aninverted staggered transistor may be used. A top-gate transistor or abottom-gate transistor may be used. A semiconductor material used forthe transistors is not particularly limited, and for example, silicon orgermanium can be used. Alternatively, an oxide semiconductor containingat least one of indium, gallium, and zinc, such as an In—Ga—Zn-basedmetal oxide, may be used.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle-crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. It is preferable that a semiconductorhaving crystallinity be used, in which case deterioration of thetransistor characteristics can be suppressed.

The light-emitting element included in the light-emitting panel includesa pair of electrodes (the lower electrode 431 and the upper electrode435); and the EL layer 433 between the pair of electrodes. One of thepair of electrodes functions as an anode and the other functions as acathode.

The light-emitting element may have any of a top emission structure, abottom emission structure, and a dual emission structure. A conductivefilm that transmits visible light is used as the electrode through whichlight is extracted. A conductive film that reflects visible light ispreferably used as the electrode through which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO), indium zinc oxide,zinc oxide, or zinc oxide to which gallium is added. Alternatively, afilm of a metal material such as gold, silver, platinum, magnesium,nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium,or titanium; an alloy containing any of these metal materials; or anitride of any of these metal materials (e.g., titanium nitride) can beformed thin so as to have a light-transmitting property. Alternatively,a stack of any of the above materials can be used as the conductivefilm. For example, a stacked film of ITO and an alloy of silver andmagnesium is preferably used, in which case conductivity can beincreased. Further alternatively, graphene or the like may be used.

For the conductive film that reflects visible light, for example, ametal material such as aluminum, gold, platinum, silver, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or analloy containing any of these metal materials can be used. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. An alloy containing aluminum (an aluminum alloy) such as analloy of aluminum and titanium, an alloy of aluminum and nickel, or analloy of aluminum and neodymium; or an alloy containing silver such asan alloy of silver and copper, an alloy of silver, copper, andpalladium, or an alloy of silver and magnesium can be used for theconductive film. An alloy of silver and copper is preferable because ofits high heat resistance. Furthermore, when a metal film or a metaloxide film is stacked in contact with an aluminum alloy film, oxidationof the aluminum alloy film can be prevented. Examples of a material forthe metal film or the metal oxide film are titanium and titanium oxide.Alternatively, the above conductive film that transmits visible lightand a film containing a metal material may be stacked. For example, astacked film of silver and ITO or a stacked film of an alloy of silverand magnesium and ITO can be used.

Each of the electrodes can be formed by an evaporation method or asputtering method. Alternatively, a discharging method such as an inkjetmethod, a printing method such as a screen printing method, or a platingmethod may be used.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the lower electrode 431 and the upperelectrode 435, holes are injected to the EL layer 433 from the anodeside and electrons are injected to the EL layer 433 from the cathodeside. The injected electrons and holes are recombined in the EL layer433 and a light-emitting substance contained in the EL layer 433 emitslight.

The EL layer 433 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 433 may further include one ormore layers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a highelectron-transport property and a hole-transport property), and thelike.

For the EL layer 433, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may also beused. Each of the layers included in the EL layer 433 can be formed byany of the following methods; an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an inkjetmethod, a coating method, and the like.

In the element layer 301, the light-emitting element is preferablyprovided between a pair of insulating films with low water permeability.Thus, an impurity such as water can be prevented from entering thelight-emitting element, leading to prevention of a decrease in thereliability of the light-emitting device.

As an insulating film with low water permeability, a film containingnitrogen and silicon (e.g., a silicon nitride film or a silicon nitrideoxide film), a film containing nitrogen and aluminum (e.g., an aluminumnitride film), or the like can be used. Alternatively, a silicon oxidefilm, a silicon oxynitride film, an aluminum oxide film, or the like canbe used.

For example, the water vapor transmittance of the insulating film withlow water permeability is lower than or equal to 1×10⁻⁵ [g/m²·day],preferably lower than or equal to 1×10⁻⁶ [g/m²·day], further preferablylower than or equal to 1×10⁻⁷ [g/m²·day], still further preferably lowerthan or equal to 1×10⁻⁸ [g/m²·day].

The substrate 303 has a light-transmitting property and transmits atleast light emitted from the light-emitting element included in theelement layer 301. The substrate 303 has flexibility. The refractiveindex of the substrate 303 is higher than that of the air.

An organic resin, which has a specific gravity smaller than that ofglass, is preferably used for the substrate 303, in which case thelight-emitting device can be more lightweight as compared with the casewhere glass is used.

Examples of a material having flexibility and a light-transmittingproperty with respect to visible light include glass that is thin enoughto have flexibility, polyester resins such as polyethylene terephthalate(PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, apolyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC)resin, a polyethersulfone (PES) resin, a polyamide resin, a cycloolefinresin, a polystyrene resin, a polyamide imide resin, and a polyvinylchloride resin. In particular, a material whose thermal expansioncoefficient is low is preferred, and for example, a polyamide imideresin, a polyimide resin, or PET can be suitably used. A substrate inwhich a glass fiber is impregnated with an organic resin or a substratewhose thermal expansion coefficient is reduced by mixing an organicresin with an inorganic filler can also be used.

The substrate 303 may have a stacked structure of a layer of any of theabove-mentioned materials and a hard coat layer (e.g., a silicon nitridelayer) which protects a surface of the light-emitting device from damageor the like, a layer (e.g., an aramid resin layer) which can dispersepressure, or the like. Furthermore, to suppress a decrease in thelifetime of the light-emitting element due to moisture and the like, theinsulating film with low water permeability may be included in thestacked structure.

The bonding layer 305 has a light-transmitting property and transmits atleast light emitted from the light-emitting element included in theelement layer 301. The refractive index of the bonding layer 305 ishigher than that of the air.

For the bonding layer 305, a resin that is curable at room temperature(e.g., a two-component-mixture-type resin), a light curable resin, athermosetting resin, or the like can be used. Examples of such resinsinclude an epoxy resin, an acrylic resin, a silicone resin, and a phenolresin. In particular, a material with low moisture permeability, such asan epoxy resin, is preferred.

Further, the resin may include a drying agent. For example, a substancethat adsorbs moisture by chemical adsorption, such as oxide of analkaline earth metal (e.g., calcium oxide or barium oxide), can be used.Alternatively, a substance that adsorbs moisture by physical adsorption,such as zeolite or silica gel, may be used. The drying agent ispreferably included because it can prevent an impurity such as moisturefrom entering the light-emitting element, thereby improving thereliability of the light-emitting device.

In addition, it is preferable to mix a filler with a high refractiveindex (e.g., titanium oxide) into the resin, in which case theefficiency of light extraction from the light-emitting element can beimproved.

The bonding layer 305 may also include a scattering member forscattering light. For example, the bonding layer 305 can be a mixture ofthe above resin and particles having a refractive index different fromthat of the resin. The particles function as the scattering member forscattering light.

The difference in refractive index between the resin and the particleswith a refractive index different from that of the resin is preferably0.1 or more, further preferably 0.3 or more. Specifically, an epoxyresin, an acrylic resin, an imide resin, a silicone resin, or the likecan be used as the resin, and titanium oxide, barium oxide, zeolite, orthe like can be used as the particles.

Particles of titanium oxide or barium oxide are preferable because theyscatter light excellently. When zeolite is used, it can adsorb watercontained in the resin and the like, thereby improving the reliabilityof the light-emitting element.

The insulating layer 405 and the insulating layer 455 can each be formedusing an inorganic insulating material. It is particularly preferable touse the insulating film with low water permeability, in which case ahighly reliable light-emitting panel can be provided.

The insulating layer 407 has an effect of preventing diffusion ofimpurities into a semiconductor included in the transistor. As theinsulating layer 407, an inorganic insulating film such as a siliconoxide film, a silicon oxynitride film, or an aluminum oxide film can beused.

As each of the insulating layers 409, 409 a, and 409 b, an insulatingfilm with a planarization function is preferably selected in order toreduce surface unevenness due to the transistor or the like. Forexample, an organic material such as a polyimide resin, an acrylicresin, or a benzocyclobutene-based resin can be used. Other than suchorganic materials, it is also possible to use a low-dielectric constantmaterial (a low-k material) or the like. Note that a plurality ofinsulating films formed of these materials or inorganic insulating filmsmay be stacked.

The insulating layer 411 is provided to cover an end portion of thelower electrode 431. In order that the insulating layer 411 be favorablycovered with the EL layer 433 and the upper electrode 435 formedthereover, a side wall of the insulating layer 411 preferably has atilted surface with continuous curvature.

As a material for the insulating layer 411, a resin or an inorganicinsulating material can be used. As the resin, for example, a polyimideresin, a polyamide resin, an acrylic resin, a siloxane resin, an epoxyresin, or a phenol resin can be used. In particular, either a negativephotosensitive resin or a positive photosensitive resin is preferablyused for easy formation of the insulating layer 411.

There is no particular limitation on the method for forming theinsulating layer 411; a photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an inkjetmethod), a printing method (e.g., a screen printing method or an off-setprinting method), or the like may be used.

The insulating layer 417 can be formed using an inorganic insulatingmaterial, an organic insulating material, or the like. As the organicinsulating material, for example, a negative or positive photosensitiveresin, a non-photosensitive resin, or the like can be used. When aconductive material is used for the insulating layer 417 and theinsulating layer 417 is electrically connected to the upper electrode435, voltage drop due to the resistance of the upper electrode 435 canbe prevented. The insulating layer 417 may have either a tapered shapeor an inverse tapered shape.

Each of the insulating layers 476, 478, 491, 493, and 495 can be formedusing an inorganic insulating material or an organic insulatingmaterial. It is particularly preferable to use an insulating film with aplanarization function for each of the insulating layers 478 and 495 inorder to reduce surface unevenness due to a sensor element.

For the sealing layer 413, a resin that is curable at room temperature(e.g., a two-component-mixture-type resin), a light curable resin, athermosetting resin, or the like can be used. For example, a polyvinylchloride (PVC) resin, an acrylic resin, a polyimide resin, an epoxyresin, a silicone resin, a polyvinyl butyral (PVB) resin, an ethylenevinyl acetate (EVA) resin, or the like can be used. A drying agent maybe contained in the sealing layer 413. In the case where light emittedfrom the light-emitting element 430 is extracted outside through thesealing layer 413, the sealing layer 413 preferably includes a fillerwith a high refractive index or a scattering member. Materials for thedrying agent, the filler with a high refractive index, and thescattering member are similar to those that can be used for the bondinglayer 305.

Each of the conductive layers 356, 357, 494, and 496 can be formed usingthe same material and the same step as a conductive layer included inthe transistor or the light-emitting element. The conductive layer 480can be formed using the same material and the same step as a conductivelayer included in the transistor.

For example, each of the conductive layers can be formed to have asingle-layer structure or a stacked-layer structure using any of metalmaterials such as molybdenum, titanium, chromium, tantalum, tungsten,aluminum, copper, neodymium, and scandium, and an alloy materialcontaining any of these elements. Each of the conductive layers may beformed using a conductive metal oxide. As the conductive metal oxide,indium oxide (e.g., In₂O₃), tin oxide (e.g., SnO₂), zinc oxide (ZnO),ITO, indium zinc oxide (e.g., In₂O₃—ZnO), or any of these metal oxidematerials in which silicon oxide is contained can be used.

Each of the conductive layers 408, 412, 510 a, and 510 b can also beformed using any of the above metal materials, alloy materials, andconductive metal oxides.

Each of the conductive layers 472, 474, 481, and 483 is a conductivelayer with a light-transmitting property. The conductive layer can beformed using, for example, indium oxide, ITO, indium zinc oxide, zincoxide, zinc oxide to which gallium is added, or the like. The conductivelayer 470 can be formed using the same material and the same step as theconductive layer 472.

As the conductive particles 492, particles of an organic resin, silica,or the like coated with a metal material are used. It is preferable touse nickel or gold as the metal material because contact resistance canbe reduced. It is also preferable to use particles each coated withlayers of two or more kinds of metal materials, such as particles coatedwith nickel and further with gold.

For the connector 415, it is possible to use a paste-like or sheet-likematerial which is obtained by mixture of metal particles and athermosetting resin and for which anisotropic electric conductivity isprovided by thermocompression bonding. As the metal particles, particlesin which two or more kinds of metals are layered, for example, nickelparticles coated with gold are preferably used.

The coloring layer 459 is a colored layer that transmits light in aspecific wavelength range. For example, a red (R) color filter fortransmitting light in a red wavelength range, a green (G) color filterfor transmitting light in a green wavelength range, a blue (B) colorfilter for transmitting light in a blue wavelength range, or the likecan be used. Each coloring layer is formed in a desired position withany of various materials by a printing method, an inkjet method, anetching method using a photolithography method, or the like.

The light-blocking layer 457 is provided between the adjacent coloringlayers 459. The light-blocking layer 457 blocks light emitted from theadjacent light-emitting element, thereby preventing color mixturebetween adjacent pixels. Here, the coloring layer 459 is provided suchthat its end portion overlaps with the light-blocking layer 457, wherebylight leakage can be reduced. The light-blocking layer 457 can be formedusing a material that blocks light emitted from the light-emittingelement, for example, a metal material, a resin material including apigment or a dye, or the like. Note that the light-blocking layer 457 ispreferably provided in a region other than the light extraction portion304, such as the driver circuit portion 306, as illustrated in FIG. 10B,in which case undesired leakage of guided light or the like can beprevented.

The insulating layer 461 covering the coloring layer 459 and thelight-blocking layer 457 is preferably provided because it can preventan impurity such as a pigment included in the coloring layer 459 or thelight-blocking layer 457 from diffusing into the light-emitting elementor the like. For the insulating layer 461, a light-transmitting materialis used, and an inorganic insulating material or an organic insulatingmaterial can be used. The insulating film with low water permeabilitymay be used for the insulating layer 461.

Example of Manufacturing Method

Next, an example of a method for manufacturing a light-emitting devicewill be described with reference to FIGS. 14A to 14C and FIGS. 15A to15C. Here, the manufacturing method is described using thelight-emitting device of Specific Example 1 (FIG. 10B) as an example.

First, a separation layer 503 is formed over a formation substrate 501,and the insulating layer 405 is formed over the separation layer 503.Next, the transistor 440, the conductive layer 357, the insulating layer407, the insulating layer 409, the light-emitting element 430, and theinsulating layer 411 are formed over the insulating layer 405. Anopening is formed in the insulating layers 411, 409, and 407 to exposethe conductive layer 357 (see FIG. 14A).

In addition, a separation layer 507 is formed over a formation substrate505, and the insulating layer 455 is formed over the separation layer507. Next, the light-blocking layer 457, the coloring layer 459, and theinsulating layer 461 are formed over the insulating layer 455 (see FIG.14B).

The formation substrate 501 and the formation substrate 505 can each bea glass substrate, a quartz substrate, a sapphire substrate, a ceramicsubstrate, a metal substrate, or the like.

For the glass substrate, for example, a glass material such asaluminosilicate glass, aluminoborosilicate glass, or barium borosilicateglass can be used. When the temperature of heat treatment performedlater is high, a substrate having a strain point of 730° C. or higher ispreferably used. Note that when containing a large amount of bariumoxide (BaO), the glass substrate can be heat-resistant and morepractical. Alternatively, crystallized glass or the like may be used.

In the case where a glass substrate is used as the formation substrate,an insulating film such as a silicon oxide film, a silicon oxynitridefilm, a silicon nitride film, or a silicon nitride oxide film ispreferably formed between the formation substrate and the separationlayer, in which case contamination from the glass substrate can beprevented.

The separation layer 503 and the separation layer 507 each have asingle-layer structure or a stacked-layer structure containing anelement selected from tungsten, molybdenum, titanium, tantalum, niobium,nickel, cobalt, zirconium, zinc, ruthenium, rhodium, palladium, osmium,iridium, and silicon; an alloy material containing any of the elements;or a compound material containing any of the elements. A crystalstructure of a layer containing silicon may be amorphous, microcrystal,or polycrystal.

The separation layer can be formed by a sputtering method, a plasma CVDmethod, a coating method, a printing method, or the like. Note that acoating method includes a spin coating method, a droplet dischargemethod, and a dispensing method.

In the case where the separation layer has a single-layer structure, atungsten layer, a molybdenum layer, or a layer containing a mixture oftungsten and molybdenum is preferably formed. Alternatively, a layercontaining an oxide or an oxynitride of tungsten, a layer containing anoxide or an oxynitride of molybdenum, or a layer containing an oxide oran oxynitride of a mixture of tungsten and molybdenum may be formed.Note that the mixture of tungsten and molybdenum corresponds to an alloyof tungsten and molybdenum, for example.

In the case where the separation layer is formed to have a stacked-layerstructure including a layer containing tungsten and a layer containingan oxide of tungsten, the layer containing an oxide of tungsten may beformed as follows: the layer containing tungsten is formed first and aninsulating film formed of an oxide is formed thereover, so that thelayer containing an oxide of tungsten is formed at the interface betweenthe tungsten layer and the insulating film. Alternatively, the layercontaining an oxide of tungsten may be formed by performing thermaloxidation treatment, oxygen plasma treatment, nitrous oxide (N₂O) plasmatreatment, treatment with a highly oxidizing solution such as ozonewater, or the like on the surface of the layer containing tungsten.Plasma treatment or heat treatment may be performed in an atmosphere ofoxygen, nitrogen, or nitrous oxide alone, or a mixed gas of any of thesegasses and another gas. Surface condition of the separation layer ischanged by the plasma treatment or heat treatment, whereby adhesionbetween the separation layer and the insulating film formed later can becontrolled.

Each of the insulating films can be formed by a sputtering method, aplasma CVD method, a coating method, a printing method, or the like. Forexample, the insulating layer is formed at a temperature of higher thanor equal to 250° C. and lower than or equal to 400° C. by a plasma CVDmethod, whereby the insulating layer can be a dense film with very lowwater permeability.

Then, a material for the sealing layer 413 is applied to a surface ofthe formation substrate 505 over which the coloring layer 459 and thelike are formed or a surface of the formation substrate 501 over whichthe light-emitting element 430 and the like are formed, and theformation substrate 501 and the formation substrate 505 are attachedwith the sealing layer 413 positioned therebetween (see FIG. 14C).

Next, the formation substrate 501 is separated, and the exposedinsulating layer 405 and the substrate 401 are attached to each otherwith the bonding layer 403. Furthermore, the formation substrate 505 isseparated, and the exposed insulating layer 455 and the substrate 303are attached to each other with the bonding layer 305. Although thesubstrate 303 does not overlap with the conductive layer 357 in FIG.15A, the substrate 303 may overlap with the conductive layer 357.

Any of a variety of methods can be used as appropriate for theseparation process. For example, when a layer including a metal oxidefilm is formed as the separation layer on the side in contact with thelayer to be separated, the metal oxide film is embrittled bycrystallization, whereby the layer to be separated can be separated fromthe formation substrate. Alternatively, when an amorphous silicon filmcontaining hydrogen is formed as the separation layer between theformation substrate having high heat resistance and the layer to beseparated, the amorphous silicon film is removed by laser lightirradiation or etching, whereby the layer to be separated can beseparated from the formation substrate. Alternatively, after a layerincluding a metal oxide film is formed as the separation layer on theside in contact with the layer to be separated, the metal oxide film isembrittled by crystallization, and part of the separation layer isremoved by etching using a solution or a fluoride gas such as NF₃, BrF₃,or ClF₃, whereby the separation can be performed at the embrittled metaloxide film. Furthermore, a method may be used in which a film containingnitrogen, oxygen, hydrogen, or the like (for example, an amorphoussilicon film containing hydrogen, an alloy film containing hydrogen, analloy film containing oxygen, or the like) is used as the separationlayer, and the separation layer is irradiated with laser light torelease the nitrogen, oxygen, or hydrogen contained in the separationlayer as a gas, thereby promoting separation between the layer to beseparated and the formation substrate. Alternatively, it is possible touse a method in which the formation substrate provided with the layer tobe separated is removed mechanically or by etching using a solution or afluoride gas such as NF₃, BrF₃, or ClF₃, or the like. In this case, theseparation layer is not necessarily provided.

Furthermore, the separation process can be conducted easily bycombination of the above-described separation methods. In other words,separation can be performed with physical force (by a machine or thelike) after performing laser light irradiation, etching on theseparation layer with a gas, a solution, or the like, or mechanicalremoval with a sharp knife, scalpel or the like so that the separationlayer and the layer to be separated can be easily separated from eachother.

Separation of the layer to be separated from the formation substrate maybe carried out by filling the interface between the separation layer andthe layer to be separated with a liquid. Furthermore, the separation maybe conducted while pouring a liquid such as water.

As another separation method, in the case where the separation layer isformed using tungsten, it is preferable that the separation be performedwhile etching the separation layer using a mixed solution of ammoniumwater and a hydrogen peroxide solution.

Note that the separation layer is not necessary in the case whereseparation at the interface between the formation substrate and thelayer to be separated is possible. For example, glass is used as theformation substrate, an organic resin such as polyimide is formed incontact with the glass, and an insulating film, a transistor, and thelike are formed over the organic resin. In this case, heating theorganic resin enables the separation at the interface between theformation substrate and the organic resin. Alternatively, separation atthe interface between a metal layer and the organic resin may beperformed in the following manner: the metal layer is provided betweenthe formation substrate and the organic resin and current is made toflow in the metal layer so that the metal layer is heated.

Lastly, an opening is formed in the insulating layer 455 and the sealinglayer 413 to expose the conductive layer 357 (see FIG. 15B). In the casewhere the substrate 303 overlaps with the conductive layer 357, theopening is formed also in the substrate 303 and the bonding layer 305(see FIG. 15C). The method for forming the opening is not particularlylimited and may be, for example, a laser ablation method, an etchingmethod, an ion beam sputtering method, or the like. As another method, acut may be made in a film over the conductive layer 357 with a sharpknife or the like and part of the film may be separated by physicalforce.

In the above-described manner, the light-emitting panel can bemanufactured.

As described above, the light-emitting panel of this embodiment includestwo substrates; one is the substrate 303 and the other is the substrate401 or the substrate 402. The light-emitting panel can be formed withtwo substrates even when including a touch sensor. Owing to the use ofthe minimum number of substrates, improvement in light extractionefficiency and improvement in clarity of display can be easily achieved.

Examples of the electronic devices to which the flexible light-emittingdevice is applied include television sets (also referred to astelevisions or television receivers), monitors of computers or the like,cameras such as digital cameras or digital video cameras, digital photoframes, mobile phones (also referred to as cellular phones or cellularphone devices), portable game consoles, portable information terminals,audio reproducing devices, large-sized game machines such as pachinkomachines, and the like.

This embodiment can be implemented in an appropriate combination withany of the structures described in the other embodiments.

This application is based on Japanese Patent Application serial no.2013-150236 filed with Japan Patent Office on Jul. 19, 2013, the entirecontents of which are hereby incorporated by reference.

1. A light-emitting device comprising: a first substrate and a secondsubstrate; a first hinge comprising a first hinge piece and a secondhinge piece; and a flexible component, wherein the first hinge piece isfixed to a first side of the first substrate, wherein the second hingepiece is fixed to a first side of the second substrate, wherein a thirdside of the first substrate which is perpendicular to the first side ofthe first substrate and a third side of the second substrate which isperpendicular to the first side of the second substrate are the samelength, wherein a second side of the first substrate is opposite of thefirst side of the first substrate, wherein a second side of the secondsubstrate is opposite of the first side of the second substrate, whereinthe flexible component is attached to the first substrate and the secondsubstrate, wherein, when the light-emitting device is in a bent state,the first substrate overlaps with the second substrate and the secondside of the second substrate is between the first side of the firstsubstrate and the second side of the first substrate when seen from adirection which is perpendicular to a surface of the second substrate,and wherein, when the light-emitting device is in the bent state, theflexible component is between the first substrate and the secondsubstrate.
 2. The light-emitting device according to claim 1, wherein afirst slide function is provided in the second hinge piece, and whereinthe second substrate is configured to move in a horizontal directionwith the first slide function.
 3. The light-emitting device according toclaim 1, further comprising: a first rack and a first pinionmechanically connected to each other, wherein the first hinge furthercomprises a first shaft, wherein the first rack is fixed to the firstside of the second substrate, wherein a center of the first pinion isfixed to the first shaft, and wherein the first shaft is fixed to thefirst hinge piece.
 4. The light-emitting device according to claim 1,wherein the first substrate and the second substrate are connected toeach other with two sets of the first hinge.
 5. The light-emittingdevice according to claim 3, further comprising: a third substrate; anda second hinge comprising a third hinge piece and a fourth hinge piece,wherein the second substrate is fixed to the fourth hinge piece, andwherein the third substrate is connected to the third hinge piece sothat the third substrate slides with respect to the third hinge piecewhen the third substrate is rotated with respect to the secondsubstrate.
 6. A light-emitting device comprising: a first substrate anda second substrate; a first hinge comprising a first hinge piece and asecond hinge piece; and a flexible component, wherein the first hingepiece is fixed to a first side of the first substrate, wherein thesecond hinge piece is fixed to a first side of the second substrate,wherein a second side of the first substrate is opposite of the firstside of the first substrate, wherein a second side of the secondsubstrate is opposite of the first side of the second substrate, whereinthe flexible component is attached to a first surface of the firstsubstrate and a first surface of the second substrate, wherein, when thelight-emitting device is in a bent state, the first substrate overlapswith the second substrate and the second side of the second substrate isbetween the first side of the first substrate and the second side of thefirst substrate when seen from a direction which is perpendicular to asurface of the second substrate, and wherein, when the light-emittingdevice is in the bent state, a second surface of the first substrate anda second surface of the second substrate face each other.
 7. Thelight-emitting device according to claim 6, wherein a third side of thefirst substrate which is perpendicular to the first side of the firstsubstrate and a third side of the second substrate which isperpendicular to the first side of the second substrate are the samelength.
 8. The light-emitting device according to claim 6, wherein afirst slide function is provided in the second hinge piece, and whereinthe second substrate is configured to move in a horizontal directionwith the first slide function.
 9. The light-emitting device according toclaim 6, further comprising: a first rack and a first pinion, whereinthe first hinge further comprises a first shaft, wherein the first rackis fixed to the first side of the second substrate, wherein a center ofthe first pinion is fixed to the first shaft, and wherein the firstshaft is fixed to the first hinge piece.
 10. The light-emitting deviceaccording to claim 6, further comprising: a first rack; a first pinion;a second pinion; and an intermediate gear, wherein the first rack isfixed to a corner of the second substrate, wherein a center of the firstpinion is fixed to a first shaft which is fixed to the second hingepiece, wherein a center of the second pinion is fixed to a second shaftwhich is fixed to the first hinge piece, wherein teeth of the firstpinion and teeth of the second pinion engage with each other through theintermediate gear, wherein a center of the intermediate gear is fixed toa third shaft which is fixed to the second hinge piece, and wherein thefirst rack and the first pinion are mechanically connected to eachother.